*{
    margin:0;
    padding:0;
    box-sizing: border-box;
}
.content{
    width:1200px;
    margin:0 auto;
}
.btn1{
    width:33.33333%;
    height:100px;
    background: #f1f1f1;
    float: left;
}
/*清楚浮动*/
.content::after{
    content:"";
    display:table;
    clear: both;
}
@media(max-width:600px){
    .content{
        width:90%;
    }
    .btn1{
        width:90%;
    }
}
